Abstract: Analyzing the all kings of mining and geological environmental information obtained by mine video monitering sysyem effectively can provide the accurate basis for the formulation of underground mining scheme and disaster assistance.Due to the existing factors of uneven illumination and high concentration of dust,the acquistion of the high quality images of the mine video monitoring sysyems are affected seriously.Combing with wavelet transform,a new improved threshold denoising method in wavelet transform domain is proposed.Firstly,the mine video monitoring image is conducted three-layers wavelet decomposition,the low-frequency wavelet decomposition coefficients and high-frequency wavelet decomposition coefficients are obtained;then,the background image in spatial domain is acquired by conducting low-frequency wavelet decomposition coefficients reconstruction,besides that,the Wiener filtering algorithm is used to deal with the small amount noises existed in the background image in spatial domain;thirdly,according to the deficiencies of the classical wavelet hard and soft threshold denoising models,a new improved threshold denoising model is put forword,the thresholds of the improved denoising model can be obtained based on the different of the high-frequency wavelet decomposition coefficients,it is used to filter out the noises in the high-frequency wavelet decomposition coefficients of different layers of wavelet decomposition,the filtered high-frequency wavelet decomposition coefficients are conducted coefficients reconstruction,so the detailed image in spatial domain is get;finally,the filtered background image in spatial domain and the filtered detailed image in spatial domain are superimposed to obtained the mine video monitoring image with high definition.The experimental data of the one mine video monitoring images acquired from a coal mine in Inner Mongolia,the experimental results show that the denoising effects of the denoising method proposed in this paper is superior to the classical wavelet hard and soft denoising models and two existed improved wavelet threshold denoising models.The experimental results further show that the denoising method proposed in this papaer can provide some reference for improving the quality of mine video monitoring images.

Key words: Mine video monitoring system, Wavelet transform, Background image, Wiener filtering, Threshold denoising model, Detailed image